Locking plug and jack



Sept. 6, 1949. A. c. FOLLMER LOQKING PLU G AND JACK 2 Sheets-Sheet 1Filed Jan. 30', 1948 'l l n Sept. 6, 1949.

A. C. FOL LMER LOCKING PLUG AND JACK Filed Jan. 30, 1948 2 Sheets-Sheet2 gn'ucnror Patented Sept. 6, 1949 UNITED STATES PATENT OFFICE 6 Claims.(o1. 173-332) (Granted under the act of March 3, 1883, as

"amended April 30, 1928; 370' O. G. 757) The invention described in thespecification and claims may be 'manufa'cturedand used by or for theGovernment for governmental purposes, without the payment'to'me of anyroyalty thereon.

The invention relates to connectors for electrical conductors, andparticularly to those of the plug-and-jack type, and it is particularlywell suited to the production of telephone switchboard jacks and plugsand other receptacle and plug connections, especially in situationswhere rough usage, vibration, and shock may be expected. 'It' isespecially an aim to present a plug and jack wherein the plug will belocked in the jack when inserted by the ordinary practice of insert; inga plug longitudinally into a socket, but which may also be unlocked andwithdrawn by the usual motion heretofore involved in grasping andwithdrawing the ordinary plugs, without special manipulations otherwise.

It issought to present such a connector which will be useful in ceilingoutlets of armored vehicles, and elsewhere, as well as at wall and flooroutlets and portable apparatus, where head phones or other electricalunits havetheir leads connected by inserted plugs.

The weight of cord and plug will often cause the dropping of a plugfrom'its' receptacle, especially where the latter is defective; and infloor and wall outlets where gravity is less apt to cause disconnection,a plug will often be withdrawn by swinging of the extension cordconductor, or-by a person brushing thereagainst.

It is a highly important object to embody a plug and socket constructionwhich will be de pendably certain to release when the plug itself ispurposely grasped and pulled with moderate efiort, and at the same timeto present an article readily adaptable to manufacture at low cost in arugged form which will be free in large degree from liability ofderangement incident to varied uses to be expected, especially inmilitary operations and in portable installations.

It is an advantage of the invention that it makes possible theembodiment of a plug ofextremely small size suitable for use in smalltele-' phone exchanges, and generally in telephone 'or telegraphoutlets, in which the improved jack element may be substituted fora'conventionaljack with standard mounting.

' It is a further purpose to enable the attach-' and the product willcorrespond closely as to manipulation, and space requirements to priorequipment.

' It is an advantage that the device will ordinarily, in its safestform, not permit withdrawal cf the plug bypumng on the cord leadingthereto, but is adapte'd'topermit such use in case of need therefor. Itis important that the plug shall utilize the prior practice of'th'e'insulated tip contact at its extremity, and a side contact sleeve as itsstem portion so that noc'ompl'exity in circuit hook-upsshall'be'introduc'e'd.

Amon other objects of the invention it is sought 'to present' a plugwhich may be readily attached 'to lead 'cords'by the ordinaryservicem'an, lineman, or erection electrician, without liability ofconfusion'due to complications in the invention; the partsof'which'may'be'readily re placed at the job, -without requiring s ecialtools ornrietl'iods;

Additional objects, advantages and features of inventionre'side in'thecons'truction, arrangement and combination "of parts involved in theembodiment of theinventionas will appear from the following "descriptionand accompanying 'drawin'gs, wherein Figure l is a vertical section ofan exchange panel or the like with my plug'installed, the inner end ofthe plug being in elevation'and the outer end. portionp'a'rtly insection;

Figure 2' is a horizontal diametrical section through the plug cntheline 33 of Figure 1,

' Figure 3 is a similar view with the lock released;

Figure 4 is a plan'of 'th'e'blank for the lock contact;

Figure 5 is a plan of the lever dog;

Figure 6 is a cross section on the line 6-6 of Fig. 1; i 1 Figure 7 is afragmentary section of the handle of theplug showing a modified use;

There is illustrated conventionally a portion of a switchboardpanel'lm'which in the present instance is assumed to be of conductingmaterial to serve 'as'a ground, although'other mountings for jacksincluding insulating materials may be employed as required.

"Setthroughan'aperture in this panel there is a jack, socket, orreceptacle l l representing an individual'telephone outlet or otherelectrical circuit outlet. This receptacle consists in this instance ofa metal bushing 12, externally threaded to'one extremity insertedthrough the'panel, and having an integral flange l3 at its forward orouter extremity against the front of the 'panel. If found'more'convenient inassembly and servicing, however, the threaded end may beextended toward the front. A look nut I4 is engaged on the bushingagainst the rear side of the panel and against this nut there is set aninsulating washer l5, a ring terminal 16, a second insulating washer 15,a lock washer, and an assembly nut l1, clamping the last-named'parts'against the lock nut 14.

The ring terminal I6 is stamped from spring laid snugly against the flat29 of the assembly block 28. The lug is apertured to receive assembly's'crews3l by'which it isfastened to the assembly block, locking thelatter firmly against longitudinal or rotative relative movement in thecase sheet metal, and consists of a simple annular -'10 21. One of thebinding screws 30 is also engaged blank from opposite sides of whichintegral contact and lock spring arms l8 are extended radially withuniform width in this particular" instance. Intermediately of thebasesoii the arms on the in this lug; attaching the lead-in 32 whichcompletes the circuit to the case 21.

The block'28 stops within the forward limit of sliding movement of thehandle 26 on the case outer edge of the ring a short tongue i flf is ex-1 :5 2'il as'rn'ay' b'seen in Figure 1, and is bored contended therefromsuitable for the soldering-of a lead wire thereto; it isinclinedgawayfrom the panel for convenient access." .Thei'arr'ns' [8 arecurved inwardly at their bases on a short radius, and extended thence asconvergentrectilinear arms symmetrically arranged in relation to theaxis of the jack andnearly or quite contacting at their outer parts intheir normal free forzn. Thelengtl -of thesearms in their rectilinearparts 11s,.. u th t co reree t anemia an which may approximate sixtydegrees,'a lthough it mayvaryin either direction to a considerable Iexte w o e i e a afis t ne h immtion of the: device;. 'Ifhe smaller theangle the --easier nay my plug be inserted, as will appear. Near theirextremities, the arms l8are bent out- .ward atright angles, to formshort shoulders 2U, and again bent in the s ame direction as the re ti rparts, u st n ie r at i an the ho der .2 t prm stq sri w l w l engagethe head of a tip contact as will-be later .shown, to prevent closing ofthe arms toward each other farther than necessary in locking function.The structure thus describedconstitutes the complete jack or receptacle.The parts and 2! on each arm IB-may be called clasp members, since theywill clasp the head at theend of an inserted plug conductor, as willappear. The plug of this invention in the instant embodiment, comprisestwo main parts relatively movable longitudinally, one on the other,the-one being an outer tubular two-piece sleeve or handle including aknob, of insulatingmaterial, while the other part, therewithin, is acomposite member comprising a-cylindricaltubular case 2'! of conductingmaterial (its external diameter being such that it may fit slidably inthe bushing I2 and serve as a conductor-thereto for one'side of acircuit), and a release or unlocking plunger of insulating 'materiaL'tobe described. 1 H

The case 21 extends for nearly the whole length of the plug and hasfixed in its outer end por- -tion (which may be considered its rearpart) an assembly block 28 of insulating material, the forward part ofwhich is fitted snugly in the case, and the major rear portion of which,excepting theextremity; is semicircular in section, presenta ing a fiatpart 29, affording a space at one side of the block within the plug toaccommodate binding and assembly screws-"30" and 31; By a number of thelatter'the block is secured in the case 21,-and circuit wire leads 32from a cord 33 are'fastened by the'screws 30. The extreme end portion ofthe block is formed with a split semiannulus 34 concentric with theblock 28 and serving as a protective bushing for the lead-in wires. Thegap 35 in this semi-annulus allows rapid placing of the lead-in-wires inthe device without inserting them through the end of the block 28.

centrically to receive snugly through its forward part and partly acrossthe flat 29 a center con- *ductorbar-or, stem 31 of a tip contact 38fixed thereon and located a suiiicient distance forward- 20 ly ofthecase 2'! to pass between and slightly beyond the shoulders 20, but notbeyond the stops 2lfofthe 'jack'when the"for-ward art of the handle 25engages the bushing l2. The shoulder 20 then engages inwardly ofandbehind therim of the tip contact. The latter is a circularmushroom-shaped head formed on orattached to the stem, the rear side 39of the tip toward the right j.in,Figure,"1I being'conical and itselements extended at an acute angle to a plane normal to the 30 stem anddefined by a sharp-edged rim 40 on the tip formed by the junction of therear and forward surfaces of the tip. The forward part 4| ofvthe tip hasa .major conical base part; the conicalelements ofwhich are at a muchgreater 35. angle "to the planeof the rim than'th os e of the side.39,.and converge forwardly. at an 'angIeLincreasing toward the axis ofthe tip, .sothat a 'rounded apex is formed thereon, substantially asshown. Other shapessuitable for the func- =1o tion of this part may beutilized.

The, rear end of the stem 31 extends across the hat 29 as before stated,and is flattened in this part,s0, as to. receive assembly screws}!engaged therethrough and in the block=28, to hold the stem in rigidrelation with the block andlcase '21, and a binding. screw 30. is alsoprovided on this flat, holding onelead wire 32 of the circuitconnections to theplug.

Fitted slidably in the forward end portion of the case 21, there is aplunger 42, axially bored to'slide along the stem 31 and having anenlarged frusto-spherical concentric cam head 43, the base of which isplaniform and engages the extremity of the case 21 when the plunger isat its rear 5 orretracted limit of movement nearly abutting the assemblyblock 28. The plunger is slidable i forwardly we position with itsforward extremity very close to or at the" rear side of the tip 38,'and'is of such radius that in its forwardmost 0 position, it is engagedwith and holds the arms l8 ofthe ring terminal apart and clear of therim 40 of the tip 38', permitting the plug to be freely withdrawn fromthe jack.

The means for operating the plunger 42 comprises two or more lever dogs44, which are set through transverse diametrically opposite slots 45formed in the case 21 a short distance forwardly I of the assembly block28, the inner ends of these dogs being set in a circumferential'channel46 in the periphery of the plunger, and the outer ends of the dogs arein a channel 41 formed on the interior of the two-piece handle. Thischannel is formed in a metal ferrulesleeve 48,- interiorly threaded atits rear end and screwed on to a corresponding exteriorly threadedsleeve part snet of t does 9 Just ffieieii t'e eraii si n? wh sqni asurfas s extend d yersen ly of the knob 422 hases! in the tarsa iiesshds in form n ar as masheah s is t a at the bhanne 4-6 nd ea h shanne asis s. a a s a re annular g oov 99 Q I Q h h 21 s and s i h l wide thanthe i iieknsss h a $195 e w mile eih pi s ash ea h t a wh n a i n d thsash e her 11. a stamps p an mrma it the ax o the plus the r ia di ast be n he b t ens li h re a th th eg s is be arran ed a r gh ngl s to th zj 9 th plu with ut binding betw e th handle and n er asse reen; I? s osli h d h and here ara lel ani qrm sides e miiis the reminder o the chls 46 41. The s t 5 are s msi nt tent 1. udi a l 9 th Pl sh? allo t edoes t lie ns medlo silidii n e e r s lln substantially a sh wn in F u eThe lsn th oi the do s is film d .50 as o mpin e on op i acin sides I epec v sleev s i case the hand e of th us s u d hems ed qnsitud na ly oth case 21 oppo i e th direction of incl nation or the dogs. n shmqrement o the hand eas last rer edl a P e sure 9 the hand ooll a ai stthe ends of the dogs, causes them to pivot in the slots as fulcrum s,and to operate as levers against the side of the groove in the plunger,and so move theplungerlongitudinally in the plug. Wh n the lus t p isPresented n he ack-h at the "bushing I2,itenter's 'n e y ther'ein'hndmay be moved longitudinally therethrough until-j th tip 38engage's 'thearms"-'|a.*" 1r it should happen that at this time the handle islat itsoutermost position on the case 2] 0i the plug "(the plunger being then"forward) opposition of an he andle the sk s will mm dia e releas the oc.ne pa s, and withdraw t e D u The 'liandle knot} 26 inturnedatits'onterns-s i e 'e ran the e a era aafilossiil s te sa t e 1 1 pgi 'has aopening throu h which the cord 33 may freely sli'de,"s0 thatnorrnally'nonu l on 'the'c'ord'will tend to i ita s sn s s elease im lus- "However,in case of need, the space between the outer end of the 1310 1 and theassemblyblpck zzifinay be :sufii cient' 't permitknotting ofthe cordwithin the h andle; substantially as 'fshown in Figure 8, i whicn'case'a pull on the cord n s n eire esse ape ra ip' Q h'e a d s nd s nus andwithdrawal of the lug. Thisiha'nner of use will be ben cial i time mcasual wit d awa of the plug by gravity thenfo'rces less than thatrequired operate the plunger, Will go e mit disconnection by a goodpullon the cord. snsh th t n ei her po tion th r end pesi- It assures"it? and dependable connection in many'situat onswhere loose plug wouldrepresent a liability of'accident'or circuit interruption Wh e h imahs'e o e ed b th s in arms I8 to f "ar'd o' protractile movement of then er wi l so pas ex an t-Wa eF lpdenjt a'l fullon tw'ard movement of thehandle 26, i a f 'm de ira l t in e a s r 50 b el wfill tner' rwagq endof the tubular part of the handle '25 and the dogs 94. 'In the instanceillustrated a single 'protract'ile' helical wire spring egsurrounds thecase 21 within the rear part of the ferrule ,Qwhioh islarger than thecase to t e ext n if the t i hhf 'Sd. the thr aded end of'the handleknob; This spring tends to thrust the does rwar at th ir outer arts; whw hold theha d o 'wsrd 'van Pre ent i s 1? a 'r' li a iqn o t lea tprevent its loose msiv mentiwhich is its pr c al Pur osethe arms l8toprbgress' of'the plunger will tend flfl T'J U I QQYF Q FIiDd i1 Pa!-to press the plunger baclg, and continued manual P 99 2 Y 3' spec arm 9?in en i n which pressure will cause the handle to moveforvvard est embdim n a 91 known to me, it

on the case 27 operating the dog levers so as to retract the plunger.

It is significant that upon withdrawal of the plug from the jack bysimple conventional grasping and pulling of the plug, protractionoperation of the plunger will be caused, its forward movement resultingfrom leverage of the dogs due to outward movement of the handle, andcausing separation of the ends of the arms I8 until the shoulders 20clear the rim 40 of the tip 38 and permit easy withdrawal of the latter.The engagement of these shoulders by the tip theretofore will preventrearward movement of the tip and case 21, so that the describedoperation of the plunger by the handle is assured.

It will be seen from the foregoing that, due to the lightness of thehandle 26, a moderate strength in the arms l8 will be sufiicient toprevent withdrawal of the plug under very severe shocks and high inertiaforces due to movements of any structure in which the jack and plug areinstalled. The angle at which the shoulders 20 are set with respect tothe axis of the plug, and the fact that the corresponding angle of therear face 39 of the tip 38 is substantially the same, causes these partsto coact as a positive lock, preventing withdrawal of the plug as longas the arms are engaged with the tip, unless the arms themselvescollapse. This safeguards the plug against accidental withdrawal even ifa person or object should become entangled with the cord in ordinarymovements. Yet a very moderate pull ture, arrangement and combination ofparts, substitution of materials and equivalents, mechanical orotherwise, may be made without departing from the spirit of theinvention set forth in the appended claims, wherein I claim:

1. An electrical coupling comprising a receptacle having aplug-receiving passage therein, inwardly convergent spring members atthe inner end of the passage having a normal minimum spacing at theirproximal parts, a plug having a head thereon transversely larger thansaid spacing and adapted to pass and receive the said proximal parts inlooking engagement therebehind when the plug is inserted in thereceptacle, a reciprocable cam member on the plug inwardly of said headmovable toward and from the head and constructed to cam said springmembers apart at the proximal limit of movement of the cam, alongitudinally slidable handle surround- 5 ing the outer part of theplug, and motion rethe same inwardly of the head to prevent withdrawalTo f the plug, a eohtn'aiserufisrsli'dable aroundsaid conductor, toandirom a position closely adjacent said head, and;having a lateral campart thereon arranged to engage and cam apart said plug locking partsiarther than the periphery of said'head when said head is advancedbeyond the plug locking parts'and when said plunger is at thecorresponding limitjof its slidable movement, a handlearound andlongitudinally slidableonthe opposite end 'portion of theplug, leverdevices of the first'order pivotally mounted in the plug on an axistransverse to the longitudinal dimension of the plug each having one endengag with the handle and the other end engagedwiththe plunger, wherebyputwa-rd movement oi the handle will movethe cam into release engagementwith said contacts.

, 3. The structur of claim 2 wherein saidpiug includes a tubular case,said plunger beingslidably fitted therein, said handle including aconcentric tubular part slidably fitted exteriorly on the case in lappedrelation with the plunger when the latter is retracted, said plungerhavi g an external circumscribing groove therearound in its lapped part,said handle having an internal perimetral groove in its lapped partpositioned to lie in a plane with the first groove when the handle andplunger are at intermediate positions, said case having at least oneslot therethrough in said plane and a lever dog set loosely in said slothaving end parts extended into respective said grooves, said groovesbeing shaped and having divergent sides positioned to allow inclinationof the lever dog under relative reciprocation of handle and plunger. A

4. The structure of claim 3 wherein said axial conductor and plungerextend beyond the end of the case, said plunger having an annular camthereon operable between the case andcsaidhead and of greater diameterthan said head, and having a retracted position spaced inwardly from thehead and clear of said spring contacts. 7

5. alocking electi'icalplug" and jack comprising areceptaclehavingopposed resilient clasp memterse plug notched'fcn the side insertablebetween said clasp members to receive'the latterfin the notch, anaii'a'llysflidable release member on the plug mos/stamens froma releaseposition adjacent said notli' constructed to engaga'and separate theclaspjnembers from en a ement in said notch when the release member isat said position, a handle slidable over the outer end portions ofthe'plug distant 'from the notched part, and amotion reversingconnection between the handle and said release member.

6. The structure of claim 5 inwhich the motion reversing connectioncomprises a body sleeve, said release member being slidable therein,said han- "dle being withbut'andislidable along the sleeve, at least oneslot formed in the sleeve, an internal recess formed in the handlemovable across the slot in reciprocation of the handle and an externalrecess formed in the release member I movable past'the slot inmovementof the release member from and to release position in relationto the clasp members, anda lever dog of elongated form set loosely inthe slot with its end portions in respective said recesses foroscillation of the lever by reciprocation of the handle, and forreciprocatio'n of 'the release member by the inner end of the lever.

- ALVIN C. FOLLMER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITEDv STATES PATENTS Number Name Date 2,423,250 Modrey July 1, 1947FOREIGN PATENTS

